The Entertainment Software Rating Board (ESRB) has just recently rated GTA III and GTA Vice City for the PlayStation 3 system:

As with Red Dead Redemption: Game of the Year Edition showing up on BBFC before its announcement, it looks very good for a PlayStation 3 release of these PS2 classics. Hopefully Xbox 360 will be showing up soon too. - update: Rockstar has stated this won't happen due to "compatibility issues and other technical limitations".

Note: Due to an unforeseen complication, the Grand Theft Auto III PS2 Classic is not publishing with today’s Store post. We will update you when a new release date has been identified. We apologize for the inconvenience.